(Stats2.txt)
[The reference studies for the primates and Eskimos are at
the end of this page. **]
FIRST-YEAR HONG KONG UNIVERSITY STUDENTS 87.5 % MYOPIC
o Goh and Lam (Goh, W.S. and Lam, C.S., "Changes in refractive
trends and optical components of Hong Kong Chinese aged 19-39
years," Ophthal. Physiol. Opt., 14:378-382, 1994) found that
in 2000 first-year students at the University of Hong Kong,
the prevalence of myopia was 87.5%.
******************
MYOPIA PREVALENCE IS ALWAYS HIGHER THAN 92 PERCENT
FOR TAIWAN MEDICAL STUDENTS
o Lin et al (Lin, L.K., Shih, Y.F., Lee, Y.C., Hung, P.T., and
Hou, P.K., " Changes in ocular refraction and its components
among medical students - a 5-year longitudinal study", Optom.
Vis. Sci., 73:495-498, 1996) found that in a study of 345
National Taiwan University medical students, the myopia
prevalence increased from 92.8% to 95.8% over the five year
period.
******************
OPTOMETRY STUDENTS 72 PERCENT MYOPIC
o Lam and Yap (Lam, C.S. and Yap, M. "Ocular dimensions and
refraction in Chinese Orientals", Proc. Int. Soc. Eye Res.,
6:121, 1990) found that in a group of optometry students at
The Hong Kong Polytechnic University, the prevalence of myopia
was 75% in females and 69% in males.
******************
70 PERCENT MYOPIC AT AGES 16 TO 17 YEARS OLD
o Regarding the prevalence of myopia in Asian countries, Lam and
Goh (Lam, C.S. and Goh, W.S., "The incidence of refractive
errors among schoolchildren in Hong Kong in relationship with
the optical components", Clin. Exp. Optom., 74:97-103, 1991)
found that in 383 school children from ages 6 to 17 years, the
prevalence of myopia increased from 30% at ages 6-7 years, to
70% at ages 16-17 years.
******************
December 6, 2000
By Liu Shao-hua
Staff reporter
Taipei Times
Subject: Myopia Increases Among Children
One of every five children in the first grade in Taiwan's
elementary schools is myopic (nearsighted). The proportion of
myopics in this group has increased from 12.1 percent in 1995 to
20.4 percent this year, according to the results of a survey
released by the Department of Health yesterday.
The results also show that 60.7 percent of sixth graders in
elementary schools, 80.7 percent of third graders in junior high
schools, and 84.2 percent of third graders in senior high schools
suffer from myopia. In addition, the number of seriously myopic
children is also on the rise. The proportion of seriously myopic
children among sixth graders in elementary schools has increased
from 2 percent five years ago to 2.4 percent this year.
Serious myopia is defined as exceeding 600 degrees (6
diopters). Anything over 25 degrees (0.25 diopters) is myopia.
Normal eyesight is zero degrees.
"We appeal for reductions to children's work load in schools
and the amelioration of visual environments in daily life," said
Chen Tzay-jinn, director-general of the health promotion bureau,
under the health department.
The survey was conducted by the department, in cooperation
with National Taiwan University and its hospital, and involved a
sample of 12,000 students from four million students between the
ages of 7 and 18 nationwide. Myopia has been on the increase in
Taiwan ever since the first myopia survey in 1983. The department
manages the survey every four or five years.
The growth of nearsightedness among young children is thought
to result from learning to read very young and using computers
very young, Chen pointed out.
Last year, the department and the Ministry of Education
delivered official documents to kindergartens nationwide demanding
that children not be taught to read or use computers too early.
"But many teachers and parents protested against this appeal,"
said the department officials. "They questioned exactly what they
were permitted to teach if reading was not allowed."
"We do hope that parents and teachers can heighten their
awareness of myopia and understand that early learning does not
guarantee students' performance in the future, but it does bear a
strong correlation to defects in vision," Chen said. The
department also appealed for children under the age of 10 not to
be taught how to use computers.
Senior high school students suffer the highest rates of
nearsightedness, at over 84 percent. "It reached a plateau five
years ago and has not changed this year. But their myopia has
become more serious," Chen said. According to the survey, 20
percent of third graders in senior high schools are seriously
nearsighted.
Many people thought operations could cure myopia. "But the
superficial improvement of vision does not better the health of
the eye. More importantly, it might reduce people's awareness of
other problems associated with nearsightedness, apart from visual
ones," said Lin Lung-kuang, ophthalmology professor at National
Taiwan University. "Myopia cannot be cured. We have to prevent
children from becoming nearsighted. Don't let them use their
vision too early," Lin urged.
Because of the public's lack of awareness of myopia, the
department estimated its prevalence would continue to grow.
"Singapore resembles Taiwan in many respects and the extent of its
myopia problem might serve as a warning for us," Chen said.
__________________________________________________________
** Below are the 5 sources of the statistics for the
behavior of the natural primate and Eskimo eye.
1. "Visual Refractive Errors of Wild and Laboratory Monkeys", Francis
A. Young, Pullman, Washington, E.E.N.T. Digest, Volume
27, Pages 55-71, August 1965
Wild Primate eyes:
N = 598 Eyes
Mean = 0.63 Diopters
Standard Deviation = 0.72 diopters
What this means:
68 percent have refractive states from -.1 diopters to +1.35
diopters
96 percent will have refractive states from -0.8 diopters to
+2.07 diopters.
"...Animals less than 12 years old with refractive errors
between +2.0 and -0.5 diopters, normal retina and no obvious
visual difficulties are likely to have 20/20 acuity at near and
far at better-than the 5 % level of confidence.
Of some 26 rhesus monkeys within with in this range of
refractive errors ALL had 20/15 or 20/20 visual acuity. Animals
with refractive errors greater-than +2.0 diopters may have 20/20
acuity at far but not at near.
Animals with refractive errors which are more minus than -0.5
diopters will not have 20/20 acuity at far but may have it at
near."
"...Thus individuals with 20/20 acuity may have refractive
errors ranging from 0 to +3 diopters."
Francis A. Young
*****************************************
2. "Ocular Biometry of Eskimo Families", Francis A. Young, George
A. Leary, Primate Research Center, Washington State
University, Pullman, Washington, Diagnostica Ultrasonica
in Ophthalmologia, Paris, Centre National d'Ophthalmologie
des Quinze-vingts, 1973
What is the range of refractive STATES of the natural human
eye -- that have not been profoundly "affected" by 12 to 16 years
in school?
Data taken from:
"The Transmission of Refractive Errors within Eskimo
Families", 1969
Francis Young
George Leary
William Baldwin
Donald West
and
Roy Box
Eugene Harris
Curtis Johnson
Refractive STATES from age 36 to 65:
N = 143 Eskimos
Mean = +1.8 Diopters average
Sigma = 1.27 Diopters
What this data tells us about the 20/20 eye -- using a normal
distribution:
68 percent are positive:
+0.68 diopters to +3.15 diopters
Or no myopia in that percentage.
96 percent between these values:
-0.6 diopters to +4.4 diopters
It is possible to have 20/20 and a retinoscope measurement of
-0.6 diopters.
The published measured values were from
-1.95 diopters to +5.89 Diopters.
There was one Eskimo with a refractive state greater than
-1.0 diopters.
Or, 1/143 = 0.6 percent were significantly myopic.
This result compares with the "educated" Eskimos (younger)
that show average myopia of -2.07 diopters, and 87 percent were
classed as myopic, with approximately 70 percent more myopic that
-1 diopters.
Additional Remarks:
These are the indications that the refractive STATE of the
natural eye simply follows its average visual environment -- as a
fundamental process.
While we have certainly "changed" in our "habits" over the
last 200 years, to suggest that our eyes do not change with change
in average visual environment is simply a failure of concept.
I certainly agree with the "intellectual" difficulties of
plus-prevention at the threshold.
But, I believe that we must understand this issue as an
"engineering trade-off".
By this I mean that a person who has a broad perspective on
these issues can wisely accept the need for systematic use of the
plus, and keep his visual acuity as always the required DMV test.
Or, in other words, progress is only possible with change.
Those people who will attempt to stop change, will also prevent
progress.
I would rather begin the use of the preventive-plus at a
refractive STATE of zero, or slightly negative, and keep my
distant vision in the positive range as per these Eskimo eyes --
than to develop stair case myopia from that long-term "near"
environment -- compounded by an excessively strong minus lens.
Most people never "see" these statistics.
But I think we should be made aware of them -- before a minus
lens is put on us.
Many people have NO INTEREST in keeping their vision clear
(by their Snellen) for life.
For that person -- these facts have no meaning.
But if you wish to keep your distant vision, then an
understanding of these facts might help you formulate a preventive
plan with the plus.
We can never know what any person might do. That is not for
us to judge.
These fact do not "prove" that the natural eye is dynamic
with respect to "environment" or a minus lens.
The reason is that you do not have "numerical" control over
the average value of accommodation.
Only when you place a -3 diopter lens on the eye (with the
accommodation system TRACKING that -3 diopter) can you finally
prove that the natural eye "follows" an applied minus lens. That
is scientific proof.
It takes a "wise" and motivated person (or pilot) to truly
"digest" this issue and take the necessary preventive actions.
This is indeed an "Engineering trade-off".
*******************************
3. "Spectacle lenses alter eye growth and the refractive status
of young monkeys" Li-Fang Hung, M.L.J. Crawford & Earl L.
Smith, Nature Medicine, Volume 1, Number 8, August 1995
Refractive STATES of young, normal primate eyes:
N = 22 Eyes
Mean = + 4.3 diopters
Standard Deviation = 1.3 diopters.
What this means:
68 percent of natural eyes will have refractive STATES from
+3 Diopters to +5.3 diopters
96 percent will have refractive STATES between +1.7 to +6.9
Diopters.
Subject: Analysis of refractive STATE change in a school
environment -- after 8 years, from plus to minus as natural
process.
I am convinced that Jake Raphaelson was correct -- and
convinced that ONLY you can protect your own children with the
plus.
As far as I am concerned, a child with a refractive STATE of
from zero to +1/2 diopter should receive a written notification of
the potential for plus prevention.
At that stage the child would have 20/30 vision or better,
and could wear a +1.0 diopter all the time.
The lens would create 20/60 to 20/70, for a period of time,
but -- with understanding -- the child could wear it all the time.
But from the primate studies, the refractive STATE will
slowly move positive. And after three or four months the
refractive state would move towards +3/4 to +1 diopters.
This type of result is predictable from the primate studies.
But it would take a wise parent the understand this issue.
The other alternative is to BEGIN the use of a plus for all
close work, and adjusted for the child's habitual reading
distance.
****************************************
4. Massin, J. and Poujol, J. (Eds.)) Diagonstica Ultrasonica in
Ophthalmologia, Paris, Centre National d'Ophthalmologie
des Quinze-vingts, 1973
Francis Young, George Leary
Here are the statistics:
Age 9
N = 109
Mean +1.43
SD = 1.40
===================
Age 17
N = 97
Mean = -0.94
SD = 1.97
====================
Calculation:
Z = X(c) - X(t) / Sqrt [ X(c) ^2 / N(c) + X(t) / N(t)
Z = 2.37 / Sqrt [ 1.4 ^2 / 109 + 1.97 ^2 / 97 ]
Z = 9.84
=================
This compares with 95 percent (significant) and 99 percent
(highly significant). These values are 1.64 and 2.33.
Virtually certain is anything above 3.9, and this value is
far above that number.
No single study, no one assessment can be effective.
But over 30 years you would expect that we could get
"smarter" about the need for plus-prevention at the threshold.
Or at the very minimum, understand the long-term consequences
of rejecting the preventive plus at the 0.0 diotper to + 1/2
diopter phase.
Perhaps these statistics will help a parent ACCEPT the need
for the preventive plus -- even when their child as 20/20 and zero
diopters.
*************************
5. "The Distribution of Refractive Errors in Monkeys", Francis A. Young,
Exp. Eye Res. (1964) 3, 230-238,
Data: Monkeys in cages or confined enviroment for over 7 years.
N = 154 Eyes
Mean = -1.6 diopters
Sigma = 4.2 diopters
Measured spread: -22 to +5.5 diopters
The distribution of monkeys in the wild, for 598 eyes
had an approximate average of +0.7 diopters, and a
standard deviation of 0.7 diopters for comparison.
Otis